JPS58500227A - Improved autonomous terminal data communication system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Improved autonomous terminal data communication system field of invention FIELD OF THE INVENTION This invention relates generally to the field of data communications, and more particularly to data communications over a common data communications medium. Data communication is performed between multiple terminals, and each terminal is connected to all other terminals or devices. Relating to a system that autonomously accesses data communication media independently from .

Background of the invention U.S. Pat. No. 4,199,663, Autonomous Terminal Data Communication System (to Herzog) April 22, 1980, Assigned to the Applicant of this Invention) each can periodically send messages over a data communication medium such as a data bus. , and the message sent by each terminal is the same as the message sent by all other terminals. describes a data communication system that is autonomous. depending on a device Message transmission is possible only when certain protocols are satisfied. this The protocol includes approximately the ``terminal'' gap between messages specific to that terminal No message is present on the data communication medium for an equal amount of time, and the terminal First, it is necessary that a specified sending interval has elapsed since the previous message was sent. It is. The transmission interval of all terminals is the gap of all terminals and the previous The total length of all messages sent by multiple terminals since the message was sent. Consists of approximately the same length that is greater than the sum.

Such systems aim to send messages over a data communication medium. Since each connected terminal accesses the target autonomously, it is not controlled by the central bus controller. This eliminates the need to control the transmission of messages and eliminates the need for wiring between connected terminals. The reliability of the data communication system can be significantly reduced. However, the terminal must periodically send messages. In one respect, the fact that it has to be done is a drawback. For example, once the data communication medium After sending a message on the body, the device will not transmit any messages until the transmission interval has elapsed. have to wait for the message communication to begin. data communication system When designed for a very large number of attached terminals, only a small number of attached terminals can When transmitting messages, a fixed transmission interval must elapse. Therefore, the rate at which any terminal can continuously send messages and the data communication medium, thus requiring a significant portion of the time. It is clear that it is wasted.

In addition, in the case of the protocol of U.S. Patent No. 4,199,663, from any terminal The length of a continuous message is the length of a continuous message to keep periodic message sending by the terminal. It requires approximately equality in order to W? , a large amount of data is sent from − terminal to other terminal. When transmitting data, a fixed message length is required, so Only a part of the data can be transmitted within a frame, and the next part of the data cannot be transferred to the next image. It is clear that the transmission cannot be made until the interval has elapsed.

When applied to modern aircraft, data communication systems are essentially fixed-length meso The requirement to periodically transmit the ideally suited to the requirements of For example, in an aviation system, a transmitting terminal obtains information from a sensor. The data sent by the sending terminal is sent by the device connected to the receiving terminal. A closed-loop servo system that operates based on data and performs a certain control function. to do. Such applications require periodic message sending and therefore cannot be utilized. The control actions performed by the device relate the data from the sensor to a predetermined time relationship. Motsu. However, by requiring the sending of periodic messages, the system Certain aviation systems, such as surveillance and display systems, that degrade the functionality of There is also tem. A typical monitoring and display system is connected to multiple transmitting terminals. As a unit, each subsystem consists of a receiver connected to a user device. Central monitoring by accumulating large data clocks to be sent to communication terminals and display function. Furthermore, the period for accumulating data with such a system is The amount of data between and in such data blocks may be variable. Therefore, A data communication system essentially transmits periodic fixed-length messages to a terminal. and one of the subsystems has variable data at a time. The block becomes ready for transfer (ready state), but at that point other subsystems If the system is not ready for data transmission, the “Data Ready” signal is displayed. The speed of data transmission cannot be transmitted in blocks of data from the system. It is clear that this would limit the data communication medium and leave the data communication medium idle for a considerable period of time. Ru.

Accordingly, it is an object of the present invention to provide an improved autonomous terminal data communication system. shall be.

Further, the invention provides that each terminal periodically sends messages over the data communication medium. The purpose is to provide a communication system that makes it possible to

Further, the present invention allows each terminal to send variable length messages over the data communication medium. The purpose is to provide a communication/system that enables this.

Further, the present invention enables each terminal to periodically transmit data on a data communication medium. The purpose is to provide a data communication system.

Furthermore, the present invention allows each terminal to monitor the status of message transmission by other terminals in the system. Messages can be sent aperiodically or periodically on the data communication medium according to the The purpose is to provide a data communication system.

Additionally, this invention is based on all conditions for message transmission by a particular terminal of the system. We aim to provide a data communication system that makes optimal use of data communication media. purpose.

Summary of the invention The effects of the above and other objectives, which are obvious to those skilled in the art, are as follows: using a method in which multiple terminals are enabled to autonomously transmit data over a data communication medium. This is achieved by Each terminal detects the absence of a message on a data communication medium. To detect. The terminal will only send messages if the following occur consecutively: It becomes possible. That is, (1) the period of absence of a message on a data communication medium is Approximately equal to the common synchronization difference between the terminals, and (11) the data transmission medium The message absence period is terminal-specific and shorter than the synchronization gap length (synchronization gap length). The terminal gap length (period) is longer than the terminal gap length (period). This is when the length of the cap becomes substantially equal to the length of the cap.

In many cases, this method allows messages to be sent periodically from all terminals. The speed at which messages are sent from all terminals is It depends on the number of terminals sending messages and the length of these messages. Exists. If only some terminals can actually send messages, Since the speed at which messages can be sent by terminals is limited, the sending of messages by terminals is , from the previous message sent by the terminal, will be substantially identical to all of the multiple terminals. is only additionally possible when a transmission interval of a predetermined length has elapsed. Brief description of the drawing This invention can be better understood by referring to the following parts of the specification in conjunction with the accompanying drawings: can be understood.

Figure 1 shows a conventional technology that uses a data bus and has multiple terminals joining the data bus. A block diagram of the data communication system of the FIG. 2 is a block diagram of a typical subscriber terminal in the prior art. Figure 3 shows a data communication system controlled by an aperiodic variable length message protocol. a timing diagram showing the operation of the system; Figure 4 shows the end of Figure 2 used specifically to carry out the protocol shown in Figure 6. Block diagram of the terminal control unit, Figure 5 shows the subscription terminal and related utilization devices and interface units. A simplified block diagram, FIG. 6 shows the demodulator and receiver blocks in FIG. figure, FIG. 7 is a block diagram of the transmitter and modulator in FIG. 5, Figure 8 shows the aperiodic protocol, periodic protocol, and aperiodic protocol shown in Figure 6. and a combination of periodic protocols. Block diagram of the control unit, Figures 9A and 9B show that each connection terminal is equipped with a protocol control unit of the type shown in Figure 7. FIG. 2 is a timing diagram showing the operation of the data communication system provided with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Figure 1, the data communication system shown therein can be used by multiple devices. Data communication is performed between the chairs UD and UD5. In fact, the use Devices UD, ~UD5 may be connected to multiple aircraft systems, subsystems or multiple computers. Computer-related devices, such as central processing unit (CPU), input/output CIl o) Consists of devices, displays, memory, etc. Each device used UD1~U D5 comprises a device for transmitting data, a device for receiving data, or both. De The data communication system consists of multiple devices connected to a corresponding one of the devices UD5 to UD5. Equipped with several terminals (devices) TL, ~TL5, and also connects multiple terminals TL ~TL5. It also has a common data communication medium. The embodiment shown in FIG. 1 and described below. In , the data communication medium includes one or more electrical conductors, magnetic materials, waveguides or optical fibers. It consists of a data bus DB which can take many forms like a bus member. However, the date The data communication medium need not be limited to a physical device such as a data bus DB. subordinate Thus, the data communication medium may include any suitable carrier wave, such as a voice, radio or optical frequency wave; Anything that can convey information by modulating it, like a pulse, is fine. .

Figure 1 shows how each terminal exchanges data with the connected device. Data communication link 1o, connected to data bus DB by bus coupler 13 , to the data bus DB by the output 12 and the bus force 15 leading to the sending data. It has a human power 14 connected to it and receiving the data present on the data bus DB.

For example, the data bus DB reaches the physical location of the utilized devices UD~UD5. Bus couplers 13 and 14 each consist of a single twisted pair of wires. Removable core inserted into the loop adjacent to the twisted wire pair Has parts. No. 9 US Patent Applications Assigned to the Assignee of this Invention. No. 57,746, filed November 6, 1978, Current Mode Design by Herzog data or power bus.

In the embodiment shown in FIG. 1 (described below), data bus DB is used to transmit data. The data to be transmitted and received is one or more consecutive serial digital words. It has the following message format.

Referring to FIG. 2, each terminal has a demodulator 16, an input The receiver 18 demodulates the message on the data bus DB received via the receiver 18. supply the demodulated message to. The demodulated message is temporarily stored in the Nooper 18. The terminal control unit 2a controls the connected device to be used. data in an appropriate format. The terminal control unit 20 communicates with the device being used. "interface connection" information is exchanged and the received data indicators are provided to the utilizing device. do. Here again, the transmitter 22 is connected by the terminal control unit 2o. The terminal control unit 2o receives data from the available device and determines the terminal control unit 2o. in the form of a message consisting of one or more direct digital words consecutive at a time Output the received data.

Demodulator 24 modulates the message in the desired manner and outputs 12 and coupler 13. A modulated message is supplied to the data bus DB via the data bus DB.

Normally, the receiver 18 of each terminal is enabled and the transmitter The transmitter 22 is disabled (transmission prohibited). Multiple terminals TL1-T The terminal control unit 2o of L5 uses the same and unique terminal control routine or protocol. Use. This protocol allows only one terminal to transmit at a given time. Make it.

From this point of view, the data communication system described above is disclosed in U.S. Patent No. 4.199.66. It is almost the same as that explained in No. 3. Special protocol in the above patent protocol (hereinafter referred to as A-mode protocol) is also used by all terminals in steady state. The transmissions are made to occur at periodic transmission intervals.

Specifically, the A-mode protocol requires the following: +a) Transmission of each terminal The communication interval is the nominal time interval between the start of periodic data transmission by the terminal. and the length of the transmission interval of all terminals is essentially the same. . (b) Each transmitting terminal is sent with one or more data words at each communication interval. Send a single message with complete sync, label, parity and other information Noh. (c) The transmission period is fixed when periodic transmission by the terminal is required. as long as possible, as well as the duration of messages for all terminals and the gaps between all messages. The sum of the extensions required to accommodate additional terminals and additional terminals is Each message can be of any desired length, as long as the length is not exceeded. (d) The sending terminal Interruption of messages on the data bus specific to Approximately equal to the interval, a certain amount of time has elapsed since the terminal sent a previous message. Each sending terminal starts sending a message only when this occurs. (θ) all The interword gap in a message is the length of the shortest terminal gap. It's also short.

Since the A-mode protocol is specifically designed for periodic message transmission, Using the above-mentioned protocol in a data communication system of the type shown in FIG. There are limitations on how messages can be sent. For example, continuous messages from a terminal The transmission rate of the transmission is limited by the transmission interval length. A small number of terminals (i.e. terminal T When only the data bus D and TL2) are performing message transmission, the data bus D B will be idle for a considerable period of time (for example, during that time, terminals TL3 to TL will not be able to send messages. data bus DB is not utilized in an optimal manner since is clear. In addition, all terminal messages, terminal layouts, and extended Requirement that the sum of the durations of the pulses does not exceed the length of all transmitted ink-pulses. can be added to the data communication system unless the extended period is long enough. Limit the number of transmitting terminals. If the duration of the expansion gap is not long enough, each end The rate at which continuous messages can be sent by the terminal is further limited. Finally, each terminal The requirement that successive messages be of constant duration or length can be enforced at any point in time. Limit the amount of data that any given device can transmit.

This is useful when applied to data communication systems that do not require periodic message transmission. In order to avoid these restrictions, each terminal control unit 20 is further connected to a second, ie, B mode. A code seeker may also be executed. This protocol requires . (aJ each transmitting terminal is approximately equal to the length of the synchronization gap common to all (iJ terminals) (11) the absence of a message on a data path that is The absence of a message on the data bus occurs in succession approximately equal to the length of the data bus. Start sending the message only when The length of the fbl synchronization gap is all must be longer than that of the terminal gap. (C) Input of each message The length of the terminal gap is shorter than that of the smallest terminal gap.

The need for a B-mode protocol can be eliminated at each end by using a circuit like the one shown in Figure 4. can be included in the terminal control unit 20. Gap detector 32 is connected to receiver 18 When a message demodulated from is received and demodulated, and this message does not exist. provides the output signal.

Synchronous gap timer 34 is synchronized to the length of the output signal from gap detector 32. The length of the output signal from the gap detector 32 is common to all terminals. When the synchronization gap becomes approximately equal to the synchronization gap, an instantaneous output signal is output. Gah! If the output signal from the loop detector 32 ends before the synchronization signal ends, the timer 34 is reset internally. The output signal from synchronization gap 34 connects launch 36 to set and launch 36 enables AND gate 38 by providing an output signal. and passes the output signal of gap detector 32 to terminal gap timer 40. Therefore , and ke"-) 38 is enabled, the B-mode protocol Condition (1) is satisfied, and then the terminal gap timer 4o The length of each output signal of 2 is synchronized. After that, the length of the output signal of the gap detector 32 is When the terminal gap exceeds the unique terminal gap assigned to the terminal, B mode Since the protocol conditions (it and (I) are both satisfied, the terminal gap tie Master 40 provides an instantaneous transmitter enable signal to transmitter 22. This causes the transmitter 22 to send a message on the data bus DB. can. The output signal of the gap detector 32 ends before the end of the terminal In this case, the terminal gap detector 4o is internally reset. transmitter e The enable signal also resets latch 36, thus disabling AND date 38. bull. As a result, the terminal gap detector 4° will thereafter detect the memory on the data bus DB. The absence of a message causes the synchronization gap to be exceeded and the synchronization gap timer 34 is activated again. The output signal of the gap detector 32 is not input until the force signal is supplied. .

Understand in more detail how data communication systems operate in B-mode protocols For this purpose, it is necessary to also refer to FIG. Figure 6 shows the continuous flow of data communication system. FIG. 3 is a timing diagram showing a multi-cycle operation.

Each terminal TL□ to TL5 can send messages, and each message has one or more data words, each data word is of variable length, and the data It is prefixed with a label that identifies it. For many data words, the data word The boards are divided by inter gaps. The operation cycle shown in Figure 3 includes consecutive cycles T0□ and T-work. In cycle T□, each Terminals TL□ to TL5 transmit one message. That is, terminal TL, TL2 ．． TL3. TL4 and TL5 are respectively Message Materials Industry 19M2□2M3□ 9 Send M4□ and M5□. Message M111 M21, M41 and M51 each contain a single data word. This data word is of variable length. Message M3□ is divided by inter-word gaps and has equal length. Contains two data words. In cycle TI2, terminals TLl, TL2 and and TL5 are the only messages, i.e. message "12 r" M22 and M52 are Send each. Each message in cycle T12 is a single data word of variable length. Including de. Furthermore, the lengths of messages M□2 and M22 correspond to message M1. It is noted that the length is different from that of □ and M21. As shown, cycle T Yu□ is what follows message M50 of terminal TL5, and cycle T12 is It is being followed by Message Material Works of TL□.

Each terminal TL~TL5 terminal control unit) 20 creates a unique gap for the connected terminal ( (via its terminal gap timer 40). That is, gap tg+tg 2+”g3r　tgc and tg5 are respectively the terminals TL, TL2.　TL3゜T L, and TL5 (where 1; gx < tg2 < tg3 < tg 4 < tg5). In addition, the terminal control units 20 of each terminal TL□ to TL5 are all A common synchronization gap for the terminals (via its synchronization gap timer 34) is also established. .

Assume that all latches 36 are reset at the end of message M50. the After that, due to the absence of messages on the data bus DB, each terminal TL~TL5 Synchronization gap timer 34 initiates synchronization. A time equal to the synchronization gap has elapsed Each synchronous gap timer 34 then provides an output signal and a Reset the lunch 36. As a result, each AND date 38 is enabled. Therefore, each terminal gap timer 40 starts its timer operation, and the cycle T starts. Start. After a time equal to the terminal gap tg has elapsed, the terminal of the terminal TL Gap timer 4o provides a transmink enable signal, which causes The transmitter of terminal TL1 starts transmitting the message ``Material'' and sends the message to terminal TL. Since the latch 36 is reset, the &r−) 38 of the terminal TL□ is reset. and disable its terminal gap timer 40. Therefore, terminal T Continuous message transmission of Ll cannot be performed until the next synchronization gap is detected. stomach. At terminals TL2-TL5, latch 36 remains set and synchronization If a gap is detected and the message has not yet been sent by these terminals. represents something. Furthermore, the gap detector of each terminal is activated by the start of message M11. 32 stops providing its output signal, so all synchronous gap timers 34 and and terminal gap timer 40 stop timer operation (reset internally). .

At the end of message Mll, terminals TL2-TL5 start their timer operations again. end When a time equal to the end gap tg2 has elapsed, the terminal gap tie of terminal TL2 is Master 40 provides a transmitter enable signal to enable the transmitter of terminal TL2. Message M2□ starts sending message M21 from terminal TL2. Reset 14 the latch 36. Terminal gap timer 4 of terminals TL3 to TL5 0 stops the timer operation (resets) at the start of message M2□, but Obviously, the switch 36 remains set.

As shown, the terminal gap tg3. Messenger for a period equal to tg4 and tg5 If terminal TL3. TL4 and TL5 continuously send message M 3□1M4□ and M5. Send continuously. Continuous in message M3□ The inter-gap between data words must be shorter than any of the terminal gaps. terminal gap timer 4 of terminal TL and TL5. 0 ends the transmission of the first data word of message M3□ and sends message M3□ It can also be seen that starting the transmission of the second data word does not end the timer operation.

At the end of message 9 M5, all lunches 36 of terminals TL1 to TL5 are reset. This disables each ANDR port 38 so that each terminal gap The timer 40 never starts a timer operation. time equal to sync gap elapses, each synchronous gap timer 34 provides an output signal connected to it. Have them set lunch 36. As a result, all and r-) 38 are When enabled, all terminal gap timers 40 begin timer operation and Cycle 'I'll is terminated and cycle T12 is started. In cycle T engineering , terminals TL and TL2 are successively after terminal gaps tgl and tg2 have elapsed. , sends the message M, and 1422 in a manner similar to that described above. Metsuse When terminal TL22 terminates, latches 36 of terminals TL and TL2 are reset; The latches 36 of terminals TL3 to TLδ remain set. As a result, terminal T L3-TL5 and date 38 remain enabled and their ends End timer 40 starts its timer operation at the end of message M22. end After a time equal to the end gap tg2, the terminal timer 4o of the terminal TL is ( 2. Provides a transmitter enable signal (resetting launch 36). deer In response to this transmitter enable signal, terminal TL3 actually transmits. Never run. As a result, the AND date 38 of terminals TL4 and TL5 is It remains enabled.

After a time (from the end of message M2□) equal to terminal Iazzo tg4, terminal T L, terminal gap timer 4° (with latch 36 reset) Provides a data enable signal. However, this transmitter enable signal Terminal TL4 does not send a message in response to the signal. As a result, terminal T L5's AND date 38 remains enabled and its terminal gap The timer 40 continues its timer operation.

After a time (from the end of message M22) equal to the terminal gap tg5, the terminal T L5 terminal gap timer 40 (resets launch 36) transmitter provides the data enable signal. As a result, the transmitter of terminal TL5 is The transmission of the message M52 is started. When message M52 is finished, all latches 3 6 is reset and after a time equal to the sync gap, each sync gap Timer 34 provides an output signal that causes the connected launch 36 to 38 is re-enabled. Therefore, the cycle 'I'12 ends and the next cycle begins (during this period the terminal T After passing the terminal information, L engineer sends the message M engineer, and the same goes below. ).

As is clear from FIG. 6, the B-mode protocol can is sending messages continuously, and the length of continuous messages from the terminal is Continuous messages from each terminal are transmitted approximately periodically as long as the values are approximately equal. . However, as shown in Figure 6, in %B mode, the protocol sends messages aperiodically. more likely to send. In this case, the message between the long worker and the M worker is The interval (for example, the interval of cycle Tyu) is M is longer than the interval between (for example, the interval between cycles τ and 2) . Based on the B-mode protocol, the speed at which a terminal sends messages is depends on the number of terminals sending the message and the length of the message.

As the number of sending terminals and message length increases, the transmission rate decreases. Similarly, Transmission speed increases as the number of sending terminals and/or message length decreases .

The optimal usage of the data bus DB is obtained by the B protocol, but this Synchronization gap and maximum length assuming that at least one terminal is transmitting with a maximum time equal to the sum of the terminal dazzos (i.e. tg5), the synchronization gap and the maximum for a maximum time equal to the sum of the terminal gap (e.g. tg4) This is evident from the empty buses. B-mode protocol is a data bus Since we only impose the condition that the above message does not exist, continuous messages from each terminal are The length of the message can be arbitrary. Finally, B mode pro Data communication systems that operate based on protocols reset their transmission intervals. Things to do A mode that causes Adaptable to any number of sending terminals without any expansion gaps in the protocol It is Noh.

In some situations, the protocol controls of FIGS. 7, 8, 79A, and 9B A-Mode Protocol, B-Mode Protocol specifically referenced in connection with unit description It is desirable to implement a protocol or a combination thereof.

Since the receiver 18 of each terminal TL-TL5 is enabled sequentially, the data ・Messages on the bus DB are detected by the connected terminal and assigned to them by appropriate identification. It is clear that it can be transferred to the device utilizing the connection.

The 1B mode protocol is strictly enforced to ensure that only one terminal is in transmit mode at each time. It is important to be protected.

Therefore, all terminals have a synchronized IATSUZO timer 34 and a terminal IATSUZO timer 34. Since the master 40 has a stable time reference, synchronization depends on the terminal gap of each terminal. The terminal gap of each terminal cannot be shortened and the terminal gap of each terminal is close to that of other terminals. It is necessary not to do so.

Finally, the time base that establishes the intergap for each terminal is The intergap must be stable so that it does not exceed the same or all terminals. No.

For monitoring according to the B-mode protocol, each terminal has a terminal monitor 40 (second ), which includes a receiver 18, a terminal control unit 20, and a transmitter 2. The signal is input from 2. Each terminal monitor 40 has a desired interface for that connected terminal. An independent time base that establishes word coordinates, terminal gaps, and synchronization gaps. have a home base. Furthermore, the terminal monitor 40 is connected to the control unit of the connected terminal (e.g. terminal gap timer 34 and terminal gap timer 40). The actual interword gap, terminal gap and synchronization gap and their unique The desired interword gap, terminal iazzo and It has a circuit to compare the synchronization gap and the synchronization gap. If these comparisons do not match Terminal monitor 40 provides a signal to monitor enable switch 42 when , which cuts off the power to the modulator 24 and prohibits further transmission by the connected terminal. do.

To further explain the operation of the data overconfidence system, each terminal TL~TL5 is simplified. The configuration and operation of the system will be explained below.

In FIG. 5, the data bus L"B is a twisted bare wire 100 that reaches all terminals. The end of the gamma ray 100 (not shown) is short-circuited to the twist, so the device The data bus DB constitutes a single continuous current loop. on data path DB The messages are in the form of an electric current and each connected to a transmitting terminal, the bus cazoler 102 has a separable core member; The core 104 has legs formed of twisted bare wires 100. Since each wire is inserted into two adjacent loops, the bus-casoller 10 It forms one turn of the primary winding of 2. The secondary winding 106 is also wound around the core 104. The terminal stub 108 consisting of a twisted and bare wire corresponds to the transmitting terminal. It is connected.

The terminal stub 108 is the input of the demodulator 110 and the output of the demodulator 112 within the terminal. are commonly connected.

The demodulator 110 signal represents the demodulated message and is printed on the receiver 1140 input. The signal DMR is added to the signal DMR.

The configuration and operation of receiver 114 will be explained below with reference to FIG. Receiver 11 The output of 4 is the signal generated when there is no message on the data bus DB. by a receiver that addresses the ADA and the terminal (by the label already described). It consists of an output signal DR representing the data in the received valid message. output signal DR can be in parallel or serial digital form. Interface unit 1 16 is for all data exchange between the terminal and the usage device 118 connected to it. In response to the smartphone reception control signal, the received data represented by the output signal DR is is stored in interface unit 116. This received data After being converted into the desired format in the chair unit 116, the data is transferred to the usage device 118. It will be done.

The utilization device 118 sends the information to the interface unit 116 in a suitable format. supply the data that should be The data to be sent is 116, converted to parallel or serial form as appropriate, and transmitted to the transmitter. transmitter 120 in response to an interface transmission control signal ITC of 120; The output signal DT is transferred to the output signal DT. The transmitter 120 is connected to the receiver 114. In response to the signal ADA, the terminal transmits at a time determined by the protocol in use. data to be stored, label i.e. address and other information such as synchronization and parity information. An output signal DM representing the data is output in serial digital form. transmitter The signals DM and T at 120 are fed to a modulator 112 which has three states at its output. It will be done. During periods when signal T is not present, the output of modulator 112 connects the modulator to the data bus. It has high impedance so as to separate it from the DB.

During the period when the signal T exists, message transmission from the terminal is established, and the modulator 11 The output of 2 provides an output signal that alternates between the first and second levels in response to the signal DM. supply. The first and second levels are positive and negative, respectively. Output of modulator 112 The signal is fed directly to the input of demodulator 110 and also to terminal stub 108 and bus cover. It is supplied to data bus DB via puller 102.

For each message, as detailed in U.S. Pat. No. 4,199,663, The transmission format may be Manchester Pi phase level modulation. this strange In the key, successive positive and negative levels in the output signal of modulator 112 represent "1". Also, consecutive negative and positive levels in the output signal of modulator 112 represent "0". Was.

Referring to FIG. 6, modulator 110 and receiver 114 include an amplifier 130. There is. Amplifier 130 outputs l-0 during each positive level of the signal on data bus L1B. 3(g) output and also during each negative level period when the signal on data bus LIB is NEO←) provides output. During all other periods, amplifier 140 does not output. increase The pos and NE() outputs of the width transducer 130 are connected to the corresponding inputs of the ORKE"-) 132. The output of OR-DATE 132 is signal ADA. POS or NEC) When the output is provided by amplifier 130, signal ADA is at a high logic level. This means that there is a message on the data bus IJB. amplifier 1 When neither the pos output nor the NEC) output of 30 is present, the signal ADA is at a low logic level. This indicates that the message does not exist on the data path DB.

Reference is now made to the embodiment of modulator 112 and transmitter 120 in FIG. The signal ADA is then provided to the protocol control unit 140, which includes a transmit clock. A transmit clock signal χXL is also input from lock 142.

protocol control unit) 140 (a particular embodiment is described below with reference to FIG. ) is the protocol in use (this is the A-mode protocol, L-mode protocol) (or a combination of these) determine whether the car is satisfied and if so. If so, the data buffer, encoder and interface control circuit 144 and outputs an output signal T to the line driver 146 to enable the terminal to send a message. Start. Prior to this time, the circuit 144 is connected to the interface unit 116 and the data to be sent to the output signal IJT. access to the connection via the interface unit 116. data to be sent from device 118, synchronizes, labels, and prints the data. and other information into the appropriate message format. Output signal T The encoded message in response to DM is sent to line driver 146 as signal DM. Supplied. This signal Dν consists of successive first and second signals corresponding to encoded information. Has a logical level. During the period when signal T is not present, line driver 146 (fifth The output of the modulator (consisting of modulator 112 in the figure) is tri-state or high impedance. be. When signal T is present, line driver 146 each first logic of the signal DM of the interface control circuit 144 level to a corresponding positive level, and also converts each second logic level of the signal DM to a corresponding positive level. Convert to negative level. Once the message transmission is complete, circuit 144 The signal spx is supplied to the protocol control unit 140 and the protocol control unit 1 40 responds by terminating signal T and directing the output of line driver 146 to its output. return to the i-state level. Data buffer, encoder and interface - The face control circuit 144 can take many forms, but One particular embodiment useful for generating fixed length messages having the format is described in U.S. Pat. It can be seen in Figure 7 of No. 4.199,663.

Referring again to FIG. 6, signal ADA at receiver 114 is connected to the R/S flip clip. A clock control circuit consisting of a lock is supplied with 1500 Å power. Signal ADA is When the data goes low logic, which means there is no message on the bus DB, the The lock control circuit 150 is set to the first state and its output signal R is It becomes a logical level. Signal R is provided to receiver clock 152 and signal R is high. When at a logic level, receiver clock 152 is receiver clock signal RCL. It operates to output . Signal RCL and the output of amplifier 130 are both data signals. Supplied to corresponding inputs of buffer, decoder and interface control circuit 154 The data buffer, decoder and interface control circuits Line 154 shows the message information represented by the continuous level of the signal at the PO8 output. Memorize information. The circuit 154 decodes the stored message information and synchronizes it. , also performs certain tests on label and parity information, and if this test is satisfied. When the interface signal is output via the output signal DR under the control of the signal IRC, Message data is supplied to unit 116. Validly and properly addressed When a message is detected by circuit 154, signal SPD is output and the clock Set control 15-0 to its second state.

This causes signal R to go to a low logic level and de-sets receiver clock 152. This causes circuit 154 to terminate further transfer of information. data buffer , decoder and interface control circuit 154 can take many forms, but certain One particular embodiment useful for fixed length messages having a message format of No. 4,199.663, Figure 6.

Referring to FIG. 8, one particular implementation of protocol control unit 140 (FIG. 7) Examples are synchronization gap timer, transmission interval timer and terminal earphone tie. has a ma. The synchronous gap timer includes a comparator 160, a counter 162, and multiple selections. It has a selection switch 164, an inverting amplifier 166, and an AND date 168.

The transmission interval timer includes a comparator 170, a counter 172, and a plurality of selection switches. CH 174, inverting amplifier 176, AND date) 178, AND date 180 and and a switch 180. In addition, the terminal Yayazzo timer has a comparator 190 and a counter 192, an inverting amplifier 196, and an AND'r-) 198.

Focusing on the synchronization gap timer, counter 162 may contain a large number of bits (e.g., 8 bits). ) is a digital counter. The counter in the counter 162 is (counter The signal ADA (applied to the CLR input of data bus 162) is It means that sage exists. ) is cleared when it is at a high logic level. (applied to the clock or C input of counter 162) and - Increased by the output of gate 168. Comparator 160 is configured to operate on multiple bits (e.g., 8 (bit) comparators, which are connected to each stage of the counter 162. and a plurality of switches each connected to one of the plurality of selection switches 164. and a second input. Comparator 160 is synchronized with the count in counter 162. It represents the length of Iazzo and is determined by setting the plurality of selection switches 164. It serves to compare the calculated desired count with the desired count. The output signal of comparator 160 is inverted is supplied to the first power source of AND, date 168 through an amplifier 166, and is also supplied to OR. Set input of latch 169 via date 167 (whose function is explained below). and the transmit clock signal χXL is supplied to the second power of Supplied.

If the absence of a message on the data bus occurs and signals A, DA are at a low logic level. Suppose you become Bell. Since the counter 162 has already been cleared, the counter The counter in the counter 162 corresponds to the desired count set by the selection switch 164. I don't respond. Therefore, the output of comparator 160 will be at a low logic level, thereby AND gate 168 is enabled (by inverting amplifier 166). after that , in counter 162 is determined by successive pulses of signal XχL. Increased in speed. If the message (7) on the data bus continues to be absent, That is, when signal ALA maintains a low logic level, the counter in counter 162 , as set by selection switch 164 at the time corresponding to the desired synchronization gap. corresponds to the desired count, so the output signal of comparator 160 will be at a high logic level; Disable and date 168. Therefore, the output signal of comparator 160 is is held at a logical level. in response to a high logic level of the output signal of comparator 160. latch 169 is set and its output signal BIIJ goes to a high logic level; Indicates that a synchronization gap for the end of Zen has been detected. Before synchronization Yayazzo disappears The appearance of a message on the data bus results in a high logic level on signal ALIA. After the level clears counter 162, latch 16 9 is set.

Now to explain the terminal Iazzo timer, the counter 192 is a multi-bit (for example, 8 bits), and its count is (counter Cleared when the signal ADA (supplied to the CLR input of the controller) goes to a high logic level. , (supplied to the clock or C input of counter 192) and date 1 98 output. Comparator 190 has multiple bits (e.g. 8 bits). It is a comparator that compares the count in the counter 192 and the settings of the plurality of selection switches 194. and a desired count representing the terminal gap for the terminal determined by the specification.

When these two counts match, the output signal TGU of the comparator 190 goes high. It becomes a logical level. The output signal TGU is passed through the inverting amplifier 196 to the AND gate 1 98, and the signal B (from latch 169) is supplied to the The transmitter clock signal ・Supplied to the 5th person on date 198.

The message on data path DB disappears and signal ADA goes to a low logic level. Assume that it is fresh. Counter 192 is already set by the high logic level of signal ADA. is cleared, so counting is possible, but AND date 198 is not reliable. No. BIU goes to a high logic level, indicating that the aforementioned synchronization gap has been detected. is disabled until the synchronization gap is detected yet. Otherwise, counter 192 is cleared even if signal ADA goes to a low logic level. It remains as it is. The count in the counter 192 is set by the selection switch 194. does not match the desired count for the terminal gap, so signal TGU is low logic. Hold the level. A synchronization gap is detected and therefore signal BIU goes to a high logic level. Assuming that the signal kLA, is at a low logic level, the counter 1 92 increases at a rate determined by successive pulses of signal χXL. It is clear that A message is sent to the terminal on the data bus DE. when the signal ADA is not present at a certain time, i.e. during a period equal to the terminal gap When holding a low logic level, the counter in counter 192 registers the terminal gap Corresponding to the desired count representing , signal TGU goes to a high logic level and Since the key 198 is closed, the signal Tcu remains at a high logic level and the signal for the terminal is Indicates that a terminal has been detected. But before the terminal gap is detected, When a message appears on data bus DB, counter 192 outputs signal AD Cleared in response to a high logic level on A, the message on data bus DB When it disappears again, the counting operation described above is repeated.

Transmission interval, timer signal B work U1TGL! AITJ and AITJ are each 200 corresponding inputs. The protocol control unit is Assuming you only run the code protocol, the As such, signal AIU maintains a high logic level. Therefore, the synchronous A terminal gap for the terminal is detected and signals BIU and TGU are high logic respectively. When expressed as a level, the output signal STX of the AND date 200 is Become a high logic level. The output signal STX is the set input of the latch 202 and the latch 169 reset input. Protocol control unit (e.g. B-mode ・When the operating protocol is satisfied by Pro) Near #), the result is As a result, the high logic level of the signal STX sets the latch 202 and outputs the output signal T. and enable the sending of messages as described above. High logic level of signal STX The bell also resets latch 169, so signal BIU goes to a low logic level; Disable the AND date 198 of the terminal IATSUZO timer and send the signal STX. Return to low logic level. Therefore, once from the B mode protocol (signal T) K Once a message can be sent, other messages sent by the device will not be able to send the same message. Disabled until the period gap and the terminal gap for the terminal are detected consecutively. . When a message is sent by the terminal in response to signal T, the message is opened. Since the signal ADA goes to a high logic level at the beginning, counters 162 and 192 cleared and then the signal ADA goes to a low logic level (e.g. at the end of a message). It remains cleared until the Message transmission by the device ends (Data buffer, encoder and interface circuit 144 (FIG. 7) ) signal spx of ) resets latch 202 to bring signal T to a low logic level. Therefore, line driver 146 (FIG. 7) returns to the tri-state level.

In some applications, A-mode protocols or A-mode protocols and B-mode protocols may be used. Preferably, various combinations of code protocols are implemented. For this reason, send The interval timer includes a multi-bit (e.g., 8-bit) counter 172. and its count is determined by the count (supplied to the CLR input of counter 172). Cleared when the output of nd date 180 goes to a high logic level, and AND gate 17 (supplied to the clock or C input of counter 172) It is increased by the output of 8. The input of AND gate 180 is signal STX; This is provided by switch 182. Comparator 170 is a multi-bit (e.g. 8-bit) It is a comparator for the counter 172 and the plurality of selection switches 17. the desired count representing the desired transmission interval determined by the settings in 4. compare. When the two counts do not match, the output signal of comparator 170 is low. goes to logic level and enables AND date 178 via inverting amplifier 176. file. When the two counts match, the output signal of the comparator 170 is high logic. level. The output signal of comparator 170 is OR-D) 177 (its function is as follows) (described in ) to the input of AND gate 200 as signal AID. Ru.

An A-mode protocol, or a combination of an A-mode protocol and a B-mode protocol. Assume that the combination is performed. In this case switch 182 is opened. . Once the message transmission is enabled by the terminal, the signal STX is activated. The counter 172 is cleared. Signal STX is low theory Shortly after reaching the logical level, counter 172 is enabled. counter 172 The desired count represents the transmission interval set by selection switch 174. does not match the count, the output signal of comparator 170 goes to a low logic level. , the AND gate 178 is enabled and therefore the counter 172 The count of then increases at a rate determined by successive pulses of signal XXL. be done. The count is 1720, there is a message on the data bus DB. It should be noted that this will be increased regardless of the situation. Send interval elapses Since both counts match, the output signal of the comparator 170 and the signal AIU are both go to a high logic level, disabling AND date 178, and signal AI U is held at a high logic level.When the signal AIU is at a high logic level, the Assuming that issue BIU and TGU were at high logic level, and date 2 Since the signal STX of 00 becomes a high logic level, it becomes a latch 202 and (signal T ) and enable the terminal to send messages (by and date 180). It is clear that the counter 172 is also cleared.

The embodiment of the protocol control unit 140 in FIG. 8 only has an A-mode protocol; B-mode protocol only or A-mode protocol and B-mode protocol It is clear that it can be used to implement a combination of A-mode protocol K closes all the selection switches 164 (indicating the synchronous The desired count becomes zero. ), open switch 182, and select switch 1 74 and 194 as the transmission interval (this length is almost the same for all terminals) . ) and the desired count for the terminal Yayap (the length of which is terminal specific). Set it as shown. The count set by the selection switch 164 is here. Since it is zero, the output signal of comparator 160 always maintains a high logic level, and therefore It is clear that the latch 169 remains set at all times. Therefore, the signal Since BItJ holds a high logic level (depending on the high logic level of signal STX) ) The message transmission is performed by the terminal (indicated by the high logic level of signal AIU). elapsed transmission interval since the previous transmission and the logic level 1 (of the signal TGU) is possible only when both the terminal gap elapsed (represented by Become.

To run only the B-mode protocol, switch 182 must be closed or Close the selection switch 174 and set the desired synchronization gap (common to all terminals) and Selection switch 164 and and 194).

Since the desired count set in selection switch 174 is zero here, or Since the register 172 cannot be cleared by the signal STX (and date 180 is signal AIU is held at a no logic level and therefore Therefore, the transmission of the message is triggered by the synchronization signal (indicated by the high logic level of signal BIU). is represented by the progress of the cap and the subsequent logic level (of signal TGU). ) It can only be started when the terminal progress occurs.

To implement a combination of A-mode and B-mode protocols: , switch 182 is opened and the desired terminal gap, desired transmission interval and Select switches 164, 174 and 1 to represent the desired terminals, respectively. Set 94. In this combination protocol, each unit is assigned The terminal gaps identified must be unique and the synchronization gaps and transmission The interval length must be the same for all terminals. Synchronization gap and transmission The number of sending terminals as well as the length of the interval and the message length of such sending terminals are , it is clear from the timing diagrams of Figures 9A and 9B that the terminal continuously sends messages. periodic (A mode) or aperiodic (B mode)). .

The data communication system consists of terminals TL~TL5 (see Figure 1), and is related to the terminals. The terminal gaps tg yu to tg5 have a predetermined relationship (tgx < tg2 < tgs < tgt < tgs) and has the longest synchronization gap, e.g. is longer than tg5, the length of the transmission interval is longer than the synchronization gap, and All messages, terminal gaps and synchronization while the terminal is sending messages Assume that it is shorter than the sum of the numbers.

In FIG. 9A, 'active' terminals TL1 and TL2 are the only ones sending messages ”, and the remaining terminals TL3 to TL5 are “inactive” and are de-energized. Assume that At the beginning of the message) □, latch 169 of terminal TL1 is resets, disables the terminal's timer, and disables its transmit interface. The timer can also be reset (by clearing counter 172 as described above). and starts the transmission interval T. At the start of message M2□, 169 is reset, disables its terminal gap timer, and disables its transmission. Also the interval timer (by clearing counter 172 as described above) ) is reset and starts transmission interval T2□. Each message length, and At ``21'', the terminal's synchronization gap timer is reset.

on the data path for a time approximately equal to the synchronization gap after the termination of message M2□. There is no message.

Once the synchronization gap has elapsed, the output signal of each synchronization timer goes to a high logic level. Therefore, the latch 169 of the terminal TL and TL2 is set. the result , since the signal BIU of each terminal will be at a high logic level (the corresponding AND date 198 to enable each terminal gap timer. After this, the data bus There are no messages yet. (after the synchronization period has passed) After the tgU, the signal TC)U of the terminal TL goes to a high logic level. death However, since the transmission interval T11 has not yet ended, the signal A of the terminal TL IU holds low logic level. (after the synchronization period has elapsed) Terminal gap t After g2 has elapsed, the signal TGU of terminal TL2 also goes to a high logic level. but, Since the transmission interval T2□ has not yet ended, the signal at terminal TL2 is low logic. maintain a logical level. The transmission interval T1 ends at the next time, and the terminal TL, Signal BIU.

AIU and T()U go to a high logic level. On the other hand, the signal STX is at a high logic level. mode, resets latch 202, resets latch 169, and transmits the Reset the interval timer and start the transmission interval T. Signal T, respond. In response, the terminal TL starts sending the message (Z), so there is no synchronization gap. The timers and terminal gap timers of terminal TL and TL2 are reset. Mail At the end of time 2), the terminal gap timer of terminal TLl receives signal B. Since the IU is at a low logic level (due to the reset of launch 169), the disable Bullied. However, the terminal gap timer of terminal TL2 remains enabled. There is even. A message is sent on the data bus DB for a period approximately equal to the terminal number jg2. If the signal is not present, the signal TGU at terminal TL2 will be at a high logic level. Haboko At this point, the transmission interval T2□ has also elapsed, so the signal AI of terminal TL2 U also goes to high logic level. At this point, the signals BIU, AIU and and TC)U are at a high logic level, so that the signal STX is at a high logic level. , sets latch 202, resets latch 169, and resets the transmit interval. The transmission interval T22 is started by resetting the timer.

After the end of message 22, the operation of the device proceeds in the same manner as described above. . After the synchronization gap has elapsed, the latches 169 of terminals TL1 and TL2 are set; When the terminal gap Igl and the transmission interval T12 have elapsed (transmission interval The terminal TL1 starts transmitting the message TL1. Also , the terminal iazzo tgz and the transmission interval T22 elapses. terminal T23 is started), and terminal TL2 starts transmitting message M23.

Since terminal TL3 is activated while message M23 is being sent, terminal TL3 is It is on standby so that message transmission can be started upon completion of message M23.

Referring again to FIG. 8, the output signals of latches 204 and 206 are OR/K. 167 and 177, respectively. Latch 204.206 is set in response to the high logic level of the input signal PU (its output signal high logic level) and is reset in response to the high logic level of signal STX. (brings its output signal to a low logic level). When the terminal is energized, (not shown) Since the signal PU is brought to a high logic level for a short period (by means), the latch 204 and 206 are set. The high logic level of the output signal of latch 204 indicates that As a result, (or key) 167 sets launch 169 to create a synchronization gap. 1 detected, and also enables the terminal gap of the terminal.

A high logic level on the output signal of launch 206 causes (or goo) 177' ) Set the signal A/U to the /’% A logic level to “check” the transmission interval for the terminal. Represents "out".

Returning to the explanation of FIG. 9A. At the end of message 23, the terminal TL and TL Since latch 169 is reset and latch 169 of terminal TL3 is set, The terminal gap timers of terminal TL□ and TL2 are disabled, and the terminal gap timers of terminal TL3 are disabled. It can be seen that the terminal gap timer is enabled. Transmission of terminals TL and TL2 The transmission interval timer (transmission interval' □, 3 and T71. has not yet expired. 1), the timer is activated, and the terminal is sent to “Detect” the progress of the signal [7, e.g. terminal +, +,, tJ) signal AIU It becomes a logical level. Message M23 C-) After the message is finished, the data Path I) E (does not exist in soil. When terminal gap tg3 ends, terminal T143 The TGU goes to a high logic level. At this point, the signal B of terminal 1, 3 IU%AIU and Tel] are each at a high logic level, which causes the signal STX goes to a high logic level, setting latch 202 and each latch 169,2 04 and 206, and set the transmission interval time ? Reset and send Start interval T33 7). In response to note number T, terminal TL3 Since the feed of the page N axis (Lζ’l:)’J starts, the terminal TL work, TL2 and T The L3 synchronization timer and terminal ear timer are reset.

At the end of message M33, terminal TL, TL2 and T14. latch 169 are reset so their terminal VYAP timers are disabled.

After the end of message M33, no message is present on data bus DB.

After the message "33" is completed, the transmission intervals T3 and T23 have elapsed. Therefore, the signal AIU of terminals TLU and TL2 becomes a high logic level and is maintained. hold However, the latch 169 is reset and the synchronization gap is still detected. Terminal TL, TL2 is not messaged at this point. Unable to send a message.

When the synchronization gap has elapsed (after the end of message M33), each synchronization ear Since the timer output signal becomes /'%a logic level, each terminal TL, TL2 and and TL3's latch 169 are set. As a result, the signal BIU of each terminal goes high. At logic level, enable each terminal gap timer. (Synchronized Yaya When the terminal gap tgl has elapsed (after the expiration of tgl), the signal TGU of the terminal TL Become a high logic level. At this point, the signals BIU, AIU and T of the terminal TL, Since each GU goes to a high logic level, the terminal TL, sends the message M, This action resets latch 169 and sets the transmit interval. Reset the timer and start the next transmission interval. Message "End of 14" After the end, terminal 7' tgz has elapsed, so terminal TL2 sends message M24. starts transmitting, operates as described above to reset latch 169, and then reset the interval timer and start the next transmit interval. Message” 24, the transmission interval T33 has elapsed. Therefore, the terminal Even if the TL3 signals BIU and AIU are at a logic level of 1, the terminal Since g3 has not elapsed yet, there is no signal TGU, so terminal TL3 Unable to send message at this time. Following the end of Message “24” After the terminal gap tg3 elapses, each signal BIU, AIU and TGtJ goes to a high logic level, so terminal TL3 sends the message)13. sending This action resets latch 169 and sets the transmit interval timer. Reset the timer and start the next transmit interval timer. Then the device The operation proceeds in the same way.

Reference is now made to FIG. 9B. 9A until the device finishes the message “23”. Referring to the figure, it is assumed that the explanation 1- operates in a similar manner. Also, the waste floor When ÷“,・ is energized, (as mentioned above, it is set by latch 204K. 8), the latch 169 is reset (by means not shown in FIG. 8); Latch 206 is set as described above. As a result, terminal TLr, signal BI U and TGU each go to a low logic level and the terminal gap terminal of terminal TL3 The timer is disabled and its signal AIU goes to a high logic level. message ) After the end of the message, there is no message on the data bus DB. synchronization gap , the terminal latch 169 is set so that the terminal gap timer are respectively enabled. (After the synchronization time has elapsed) Terminal gap t When gl has elapsed, the signal TGU at terminal TL□ goes to a high logic level. but, Since the transmitting interval T13 has not yet elapsed, the signal AIU of the terminal TL engineer is Hold low logic level. (After the synchronization period has elapsed) Terminal gap tg 2, the terminal gap TGU of terminal TL2 also goes to a high logic level.

However, since the transmission interval T23 has not yet elapsed, the signal from terminal TL2 The AIU holds a low logic level. (after the synchronization period has elapsed) After the time tg3 has elapsed, the signal TGU at the terminal TL3 goes to the 7.i logic level.

At this point, each signal BIU, AIU, and TGU of terminal TL3 becomes high logic. Therefore, the terminal TL3 starts sending the message M34, thereby starting the lunch 16. 9 to disable its terminal gap timer and reset its latch 20. 6, reset its transmit interval timer, and reset the transmit interval timer. Start T34.

In transmitting the message M34, the transmission intervals T and T23 are It ends with. However, terminals TL and TL2 were reset during message "34". Therefore, terminals TL and TL2 cannot send messages during this time. Metsuse At the end of page 34, the terminal TL and TL2 remain set in latch 169. Therefore, its terminal gap timer is enabled. Terminal earphone tg engineer is working , the signals B, AIU and TGU of terminal TL1 go to a high logic level. Therefore, terminal TL1 starts sending message M14, and by this action it resets latch 169, resets its transmit interval timer, and transmits. The communication interval T14 is started. After the end of "Message" 14, the terminal is Yayazo After tg2 elapses, each signal BIU, lυ and TGU of terminal TL2 goes high. terminal TL2 starts sending message M24, and this operation resets its latch 169 and resets its transmit interval timer by and starts the transmission interval T24.

After message 24 ends, there are no messages on the data bus. When the synchronization gap has not elapsed (after the end of the transmission interval TL34 ends, but since latch 169 of terminal TL3 has been reset, Terminal TL3 does not send messages. Once the synchronization gap has elapsed, the terminal TL , since the latches 169 of TL2 and TL3 are set, each terminal gap The timer is enabled. (after the synchronization gap has elapsed) terminal yayazo tgl When , the signal TGU of the terminal TL goes to a high logic level. But transmission Interval T Yu. has not yet passed, so the signal AIU from terminal TL is low. Maintain logical level. (After the synchronous yap has passed) Terminal yyap tg2 has elapsed Then, the signal T()U of the terminal TL2 also becomes a high logic level. However, the transmission in Since the term T24 has not yet elapsed, the signal A of terminal TL is low logic. Hold the level. (After the synchronization Yayazzo has passed) Terminal Yayap TGS elapses Then, the signal TGU of the terminal TL3 becomes a high logic level. At this point, terminal TL3 Since each signal BIU, AIU and TG’O of terminal T becomes a high logic level, L3 starts transmitting message M3B, and this action resets latch 169. and reset its transmit interval timer to ensure consecutive transmit intervals. start the file. Transmission intervals T14 and T24 are used for message M3. in Since it is finished, message M3. When the terminal gap tg elapses after the end of , The terminal TL starts transmitting the message M. Also, the end of Message M Engineering Later, when the terminal gap tg2 has elapsed, the terminal TL2 transmits the message '25. Start.

From Figure 9A, the first message transmission by terminals TL and TL2 is periodic. I understand that. That is, the interval between message M yo 09M yo 2, message Transmission 2, "Interval and message of 13r<" 221 Interval between M23 The lengths of each space are approximately equal. Therefore, the first part of the timing diagram in FIG. A data communication system in which message communication is controlled by the A-mode protocol. Indicates that it is used. However, after messages M13 and Mn2, terminal TL3 Since message M33 is sent, the message after terminals TLl and TL2 It can be seen that is asynchronous with respect to the initial message.

That is, the interval between messages M□3r　14 is message M12. It is louder than the interval between M□3 and the interval between messages M23 and M24. The interval is greater than the interval between messages M22, "23. Therefore , the final portion of the timing diagram in Figure 9A shows that the message transmission is using the B-mode protocol. indicates that a data communication system controlled by the system is used.

Comparing Figures 9A and 9B, the synchronization gap ( 9A), or a synchronization gap (Fig. 9B) is detected. "out" means the first message sent by a newly activated terminal. Not only the actual time that the It can also be seen that the order and speed of message transmission is affected. In both states, each terminal's The transmission interval timer can control the rate at which messages are sent by the timer. Continuous message sending will depend on the terminal's synchronization earphones and terminal earphones. It turns out that it can only be executed when the zuzo has passed. This combination of protocols By using a communication method, the message communication speed of each terminal can be adjusted according to the communication interval. The data communication system supports variable length messages, but is limited to a speed determined by It is also clear that message transmission by additional terminals can be accommodated.

Although the invention has been described with reference to a preferred embodiment, it is understood that the invention is not so limited. It is clear to those skilled in the art that this is not the case. Rather, the scope of this invention is 48 should be construed only in relation to the scope of the request.

11 people’R58-500227(15)N Procedural amendment (formality) April 2, 1960 [1] Commissioner of the Patent Office 1 3. Person who makes corrections Relationship to the incident: Patent applicant 5. Date of amendment order Month 7, 1981 6. Number of inventions increased by amendment international search report

Claims (1)

[Claims] Claims of the Invention Claiming Exclusive Rights or Privileges 1. Autonomous sending of messages from multiple terminals onto data communication media In the improved method that allows each terminal to detecting the absence of a message on the data communication medium; (1) a synchronization gap that is substantially equal to the length of the synchronization gap common to all of the plurality of terminals; the absence of the message on the data communication medium; Data substantially equal to the terminal gap length less than the particle synchronization gap length K only from the terminal when the absence of the message on the communication medium occurs consecutively. Sterage and A method characterized by comprising: 2. In the method according to claim 1, sending a message from the terminal comprises: , from the previous message transmission by said terminal, to all of said plurality of terminals. be enabled when a transmission interval with the same predetermined length has elapsed. How to characterize it. 3. The method according to claim 2, wherein the length of the transmission interval is A method characterized by a longer synchronization gap than that of the synchronization gap. 4. In the method according to claim 1 or 2, the information transmitted by each of the terminals is A method characterized in that the consecutive messages sent are of variable length. 5. In the method according to claim 1 or 2, the information transmitted by each of the terminals is A method characterized in that the consecutive messages sent are of a fixed length. 6. In the method according to claim 1 or 2, the plurality of terminals A method characterized in that the messages sent are of equal length. Z. In the method according to claim 1 or 2, the transmission by the plurality of terminals is A method characterized in that the messages to be received are of unequal length. 8. The method according to claim 1 or 2, wherein at least one of the plurality of terminals Messages sent from one device are separated by an intergap word. consisting of a plurality of separate consecutive message words, each said terminal gap being A method characterized in that the length is longer than the length of the interword ears. 9. In the method according to claim 1 or 2, each said message is at least one serial digital data word transmitted over a data communication medium; A method characterized in that it has the form of a code. 10. The method of claim 9, wherein the data communication medium is a data A patent characterized in that and a data communication medium and a plurality of terminals connected to the communication medium; Synchronization gap length that is common to multiple terminals and longer than the terminal gap length a first message in response to the absence of a message on said data communication medium substantially equal to first means for providing an output signal of said terminal gap length specific to said terminal; a second output signal in response to the absence of a message on said communication medium substantially equal to second means enabled by said first output signal for providing a signal; a message on the data communication medium enabled by the first and second output signals; A data communication system, wherein the terminal includes a transmitting means for transmitting a message. 12. In the data communication system according to claim 11, each of the terminals further comprises: when a predetermined transmission interval has elapsed since the terminal's previous message transmission. sixth means for providing a sixth output signal, the length of the transmission interval being and the transmitting means is substantially the same for each of the plurality of terminals, and the transmitting means is the first. 2nd and A data communication system characterized in that it is enabled only by a sixth output signal. Tem. 13. In the data communication system according to claim 11 or 12, each The terminal further includes a receiver for receiving messages sent on the data communication medium. A data communication system characterized by having a stage. 14. In the data communication system according to claim 13, each terminal has a The receiving means is configured to exchange information with the connected device, and the receiving means forward the message received from the device to the device, and interface means for transferring a message to be transmitted from the transmitting means to the transmitting means; A data communication system characterized by: 15. Scope of Poetry In the data communication system described in paragraph 11 or 12, The message transmitting means is configured to transmit the message in the form of serial digital words. A data communication system characterized by the following features: 16. The data communication system according to claim 15, wherein the data communication A data communication system characterized in that the medium consists of a data bus. 1Z The data bus for transmitting and receiving data to and from the data bus together with other multiple terminals. In a terminal that can autonomously access (aJ) , provides a message not present signal when no message is present on said data bus. a receiver that supplies 1b) When connected to the data bus and enabled, the data bus a transmitter that sends a message to the (C1 both connected to the receiver and the transmitter, said message absent signal, and said message absent signal is synchronized with said message absent signal. substantially equal to the synchronization yyap common to each terminal accessing said data bus. When a predetermined length is reached, a synchronization gap detection signal is supplied, and the Resettable synchronization gap that is reset when the page-absent signal ends. timer, latch means for temporarily storing the synchronous jump detection signal; enabled in response to said synchronization gap detection signal and when enabled; synchronized with the message non-existence signal, the message non-existence signal is transmitted to the terminal individually. Provides a terminal gap signal when the predetermined length is substantially equal to the terminal gap of the and a reset that is reset when the terminal gap signal ends. Enable the terminal gap timer and the transmitter and synchronize the terminal gap timer possible. resetting the latch means in response to the gap detection signal and the terminal gap detection signal; a protocol control unit having dating means for setting; A terminal characterized by being equipped with. 18. The terminal according to claim 17, wherein the protocol control unit is substantially the same length for each terminal accessing the data bus after reset. Provides a transmission interval detection signal when a predetermined transmission interval ends. a resettable transmit interval timer configured to The means further enables the transmitter and resets the latching means; The synchronization gap detection signal, the terminal gap detection signal and the transmission interval to reset the transmit interval timer only in response to a signal detect signal. A device that is characterized by: 19. In the terminal according to claim 17 or 18, the synchronization gap - characterized in that the timer further comprises means for selectively adjusting the length of the synchronization gap; Terminal that is used as a sign. 2. In the terminal according to claim 17 or 18, the terminal gap characterized in that the timer comprises means for selectively adjusting the length of said terminal gap; Terminal that is used as a sign. 21. In the terminal according to claim 17 or 18, the short circuit is terminated. Specifically designed for use with data buses consisting of long twisted pairs of conductors with , further inducing the receiver and the transmitter into the twisted pair of conductors. A terminal characterized in that it is equipped with a means for coupling. 22. The terminal according to claim 18, wherein the transmission interval timer is characterized by comprising means for selectively adjusting the length of the transmission interval. terminal. 26. In the terminal according to claim 18, the protocol control unit further comprises: selectively disables the reset of the transmit interval timer and When the transmit internogle timer is enabled, the interval A terminal comprising means for supplying a detection signal. 24. The terminal according to claim 18, wherein the fO)col control unit comprises: Furthermore, when power is supplied to the terminal, the transmission interval timer A terminal comprising means for supplying a signal interval detection signal. 25. In the terminal according to claim 18 or 24, the protocol control The control unit further controls the synchronization gap timer when supplying power to the terminal. A terminal comprising means for supplying the synchronization gap detection signal.